Hydraulic lifter replacement
Hydraulic lifters automatically take up valve-train thermal clearance.
Symptoms
- A sharp tapping noise from the head, at first only when cold, then constant.
What's included
- When they wear or become coked, a characteristic ringing knock appears in the cylinder head, first only when cold and then continuously. The cause is often not the lifters themselves but the oil: oil that is too thick, old or of the wrong viscosity does not fill them in time, while a blocked passage restricts supply. We therefore check oil pressure and passage condition before replacement; otherwise new lifters will make the same noise. They are replaced as a set, then the engine is allowed to prime the system and we confirm that the noise has gone.
Additional checks
- Replacement is done as a complete set
- Confirming the knock is gone after the system primes
Why it matters
The cause is often not the lifters themselves but the oil: thick or unsuitable oil can't fill them fast enough. Without checking oil pressure and the passages, new lifters will start ticking the same way.
More details
Hydraulic lifters automatically take up the thermal clearance in the valve train. When they wear out or get coked up, a characteristic ringing knock appears in the head — at first only when cold, then constantly. The cause is often not the lifters themselves but the oil: thick, old, or wrong-viscosity oil doesn't fill them fast enough, and a clogged passage cuts off the supply. So before replacement we check the oil pressure and the condition of the passages — otherwise the new lifters would knock the same way. We replace them as a full set, and after assembly we let the engine bleed the system and check that the knock is gone.
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